1. Field of the Invention
The present invention relates to an apparatus and a method for acquiring and reading optical codes, with indication of the result of the reading itself.
2. Description of the Prior Art
In this description and the following claims, by the expression xe2x80x9coptical codexe2x80x9d, bar codes, stacked codes, that is, with a plurality of stacked bar sequences, bidimensional codes, colour codes, and the like should be meant.
Moreover, by xe2x80x9cacquisition of an optical codexe2x80x9d, the whole of illumination (or scan) of the code with a light beam, detection of the light diffused by the code, and its transformation into electric signal is meant, while by xe2x80x9creading of an optical codexe2x80x9d, the processing of the electric signal and its interpretation or decoding are meant.
Finally, by xe2x80x9cindication of the reading resultxe2x80x9d, also the mere indication of the end of the reading, or of the unsuccessful reading attempt, is meant.
Known optical code acquisition and reading apparatuses, or briefly, readers, are essentially provided with a light source for generating a light beam which is projected onto the optical code to be read, for example through slits and lenses, herein in general referred to with the expression xe2x80x9cillumination opticsxe2x80x9d, optical elements suitable to collect and focus the light diffused by the code, for example slits and lenses (in general referred to with the expression xe2x80x9creceiving opticsxe2x80x9d), photosensitive elements on which the light collected by the receiving optics is focused, suitable to detect the light diffused by the code and to convert it into an electric signal reproducing as much accurately as possible the reflectance modulations of the elements making up the code, as well as processing means for interpreting or decoding the code so as to obtain the significant information contained in it, such as for example manufacturer, name of the specific product, production lot, price, etcetera.
The operation of reading a particular optical code can give negative results for various factors, among which the imperfection of the code due, for example, to damages to the label on which it is obtained, the distance between the reader and the code, or the maintenance of said distance during the scanning time. In addition, also when the code is correctly acquired, its decoding may be impossible because, for example, it does not fall within the categories of codes known by the reader. In any case, the operator needs to know whether the code has been decoded before proceeding to read another code.
These problems are especially severe in the case of the so-called manual or hand-held readers, of the gun type.
Thus, in optical-code readers, simple indication devices are known and currently used for indicating to the user that the particular aimed optical code has been decoded by the reader.
Said indication is normally generated using a light source made up of one or more light emitting diodes (LEDs) arranged in the reader body, in the proximity of the outer surface or inside it. Since in both cases the LED must be visible from the outside, the light emitted by the LED can be refracted and/or diffused so as to be more visible towards the operator. However, the image of the reader body usually is at the edges of the operator""s field of view, whose look is focused on the optical code. This is particularly true for codes of small sizes, or for stacked codes, whose reading requires a precise movement of the hand. Thus, the perception of the lighting of the LED arranged into the reader body may not be immediate.
To improve the perception of the indication that the reading has occurred, also when the visual attention of the operator is not focused on the reader, the lighting of the LED is commonly accompanied by an acoustic signal, provided for example by an electromagnetic acoustic horn, commonly called buzzer, or beeper. However, also this provision is not totally satisfactory since the acoustic signal cannot be easily heard if the operation is carried out in a noisy environment or by an operator with auditory deficiency. Moreover, a frequently repeated acoustic signal may be annoying for the operator who must carry out very frequent readings and/or for a long time interval.
The European patent application N. 98830656.9 by the same Applicant, which represents a document of the prior art according to Art. 54 (3) EPC, describes an optical device comprising at least one illuminating assembly active on a portion of the reading area along an emission optical path, wherein said at least one illuminating assembly comprises: a light source; a diaphragm having a predetermined shape for selecting a portion of the light generated by said source; and a converging lens arranged downstream of the diaphragm for collimating the shaped light coming from the diaphragm and projecting it onto the portion of reading area.
However, said device is intended for the aiming and the visual indication of the area in which the optical code is, while the above document does not provide for any indication on the use of such a device for indicating the result of the optical code reading.
The technical problem underlying the present invention is to provide an apparatus and a method for reading optical codes, which should be capable of providing an indication of the reading result immediately perceptible by the operator.
A more ambitious object of the present invention is to provide such an apparatus and method, wherein the indication of the reading result should be more significant, that is, with greater information content.
The Applicant has found that the aforesaid technical problem can be successfully overcome by projecting a luminous figure on the optical code being read, that is to say, in the position on which the operator""s attention is focused. Moreover, making use of this inventive idea, it is possible to project, at the code, a wide range of useful information for the operator, also more complex and o elaborate than the simple indication of the end of decoding, thus satisfying also the aforesaid second object.
Thus, in a first aspect thereof, the present invention relates to an apparatus for acquiring and reading optical codes, comprising:
means for acquiring the optical code, having at least one acquisition light source,
means for reading the acquired optical code, and
means for visually indicating the reading result,
characterised in that said visual indication means comprises:
at least one indication light source, distinct from or coinciding with, the at least one acquisition light source of said acquisition means,
means for imposing an information content indicating the reading result to the light emitted by said at least one indication light source, and
means for projecting the light, having the imposed information content, substantially at the optical code.
In this description and the following claims, by xe2x80x9csubstantially at the optical codexe2x80x9d it is meant on the surface bearing the optical code and in close proximity or coincidence with the optical code itself.
Advantageously, the means for reading the optical code comprises means for communicating the acquired code to a remote processing unit and for receiving the reading result therefrom.
In an embodiment, the means for imposing the information content comprises a switch for switching on and off the at least one indication light source. This embodiment has the advantage of being very simple.
In an alternative embodiment, the means for imposing the information content comprises at least one element for selectively transmitting the light generated by the at least one indication light source. With this provision, it is possible to generate luminous figures having such shapes or hues as to be immediately recognisable by the operator as being different from the illumination line used for acquiring the code, by simply switching on and off the light source.
More in particular, the selective transmission element can be a diffractive element, a diaphragm having a predetermined shape, a slide, a reflecting surface having a predetermined shape and a shutter. For example, in the case of a diaphragm, the predetermined shape can consist in an elementary geometrical figure or it can have greater suggestive content. If the light source emits white light, it is also possible to use a colour slide. In the case of reflecting surface, the light transmitted to the projection means can alternatively be only the reflected light or only the light that is not back reflected.
As an alternative, the selective transmission element can be a diffractive element or a hologram. In this case, the information content is imposed by modifying the wave front of the light beam. The diffractive elements can be, for example, diffractive gratings, and the holograms can be, for example, Computer Generated Holograms.
In another embodiment, the means for imposing the information content comprises a driving circuit of the at least one light source. In fact, also by properly driving the light source, it is possible to obtain projected images immediately recognisable by the operator as being different from the illumination line used for acquiring the code.
Preferably, the driving circuit is suitable to drive the at least one indication light source also in such an operating condition that the at least one indication light source is the acquisition light source during the acquisition of the optical code. By providing a shared light source for both the acquisition of the optical code and the indication of the reading result, it is possible to maintain a small size of the apparatus and low costs.
Advantageously, the at least one indication light source is a light source capable of emitting light of at least two chromatic components, and the driving circuit is suitable to drive the at least one indication light source so as to generate each time light of one or more of said chromatic components. In this way, the projected image has an information content coded by its colour. Moreover, one of the generated hues can be that needed for acquiring the code.
As an alternative, the driving circuit is suitable to switch on the at least one indication light source at least intermittently. Also with this provision it is possible to generate projected images differentiated by intermittence times and distinguishable from the light emitted by the acquisition source, which is typically continuous. Moreover, the light source can coincide with the acquisition source. Said light source typically is a plurality of LEDs or a laser beam which, for the acquisition of the code, is evenly scanned on the optical code, while for the indication of the reading result, it is made intermittent or kept still so as to generate a fixed luminous point.
Alternatively, the driving circuit can be suitable to modulate the intensity of the at least one indication light source. Also in this way, it is possible to generate projected images differentiated from one another and with respect to the acquisition light, typically having even and constant intensity, both with separate light sources and with the same light sources used for the acquisition.
Typically, the means for projecting the light comprises at least one converging lens for collimating the light and focusing it substantially at the optical code.
Advantageously, the means for projecting the light is comprised of the illumination optics of the acquisition means. In this way, the apparatus can keep a small size and low cost.
Analogously, the means for projecting the light can be comprised of the receiving optics of the acquisition means.
Advantageously, the visual indication means also comprises second means for projecting the light emitted by the at least one light source or a second light emitted by a second indication light source towards the operator of the apparatus. Alternatively or in addition, the apparatus can comprise acoustic indication means associated to the visual indication means. Retaining in this way also the traditional modalities of indication, in practice the apparatus is suitable for all operating conditions.
In a second aspect thereof, the present invention relates to a method for acquiring and reading optical codes, comprising the steps of acquiring and reading an optical code through an optical code acquiring and reading apparatus, and visually indicating the result of the reading step, wherein the indication step is carried out by generating at least one luminous figure substantially at the optical code.
Preferably, the method comprises the step of discriminating the result of the reading step, and the indication step is carried out by generating a predetermined luminous figure associated to the particular discriminated result. By providing different indications associated to the particular reading result, the operator is in any case provided with an indication.
Typically, the result discrimination step is carried out by discriminating between positive result and negative result.
Preferably, the result discrimination step is carried out by discriminating among positive result and at least two different negative results. In this way, the operator can recognise, for example, if the reading is impossible due to causes relating to the optical code or due to a wrong operation of the reader, and he can thus implement, where possible, the necessary corrective measures, otherwise giving up further attempts.
Preferably, the indication step is carried out only after having repeated the reading step for a predetermined number of times receiving a negative result. In this way, temporary reading faults can be automatically overcome.
Typically, the predetermined luminous figures generated in the indication step are differentiated by hue, shape and/or dynamics of the luminous intensity. In all these ways, or by properly combining them, it is possible to transmit also complex information contents to the operator of the optical code reader.
Advantageously, the indication step is carried out by also generating at least a second luminous information at the optical code acquiring and reading apparatus.
Moreover, preferably, the luminous information generated substantially at the optical code is turned off before turning off the second luminous information at the optical code reading apparatus. With this provision, it is possible to generate a short indication in the ideal location and a longer visual indication, even if not in the ideal location.